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BUFKIT for Balloonists. Jay Trobec, Ph.D. KELOLAND TV Sioux Falls, SD jaytrobec.com. Questions we will answer. How do I install the free software on my computer? What is a computer model? What does BUFKIT tell us about… Winds aloft? Temperatures? Inversions?
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BUFKIT for Balloonists Jay Trobec, Ph.D. KELOLAND TV Sioux Falls, SD jaytrobec.com
Questions we will answer • How do I install the free software on my computer? • What is a computer model? • What does BUFKIT tell us about… • Winds aloft? • Temperatures? • Inversions? • Fog/Precipitation forecasting?
Computer models • Give us an approximation of the expected state of the atmosphere • They do not “forecast” the weather – interpretation is required • Three models are beneficial to balloonists, and can be displayed with BUFKIT software • NAM (North American Mesoscale) • GFS3 (Global Forecast System) • RUC (Rapid Update Cycle)
NAM (also called the WRF) Model • Created at 0z (6 pm CST), 6z (midnight CST), 12z (6 am CST), and 18z (noon CST) • 12 km resolution • 1 hr increments • 84 hrs
GFS Model • Created at 0z (6 pm CST), 6z (midnight CST), 12z (6 am CST), and 18z (noon CST) • 0.5 deg lat/lon • 3 hr increments • 180 hrs
RUC (also called RAP or HRRR) Model • Created every hour • 13 km resolution • 18 hrs
Overview Clouds Display Sky Box Plotted Implied .00 - .09 none Clear .10 - .24 Single Cross Hatched Few .25 - .49 Double Cross Hatched Scattered .50 - .74 Gray Broken .75 - 1.00 White Overcast
Environmental Lapse Rate (ELR) • Decrease of temperature with altitude in a stationary atmosphere • 0.5°C/100 meters • 3.5°F /1000 feet 1500 ft: 54.8° 1000 ft: 56.5° 500 ft: 58.3° Ground: 60°
Subsidence, sinking air under High pressure Warm Fronts or Cold Fronts Temperature Inversion • Thin layer in the atmosphere in which air temperature increases with height • Caused by:
Effects of Inversion • Speed of ascent slows when rising through subsidence layer
Effects of Inversion • Speed of descent slows when descending through layer
Effects of Inversion • Winds often have different directions/speeds above and below an inversion
Fog forecasting • BUFKIT utilizes “crossover temperature” technique developed by UPS • Also assesses change in humidity with height, and atmospheric stability • Technique is designed for radiational fog, not advection or other types of fog